Harold Edwin Hurst was a British hydrologist. Hurst's (1951) study on measuring the long-term storage capacity of reservoirs documented the presence of long-range dependence in hydrology. Much of Hurst's research was motivated by his empirical observations of the Nile. The Hurst exponent

Hurst exponent

The Hurst exponent is used as a measure of the long term memory of time series. It relates to the autocorrelations of the time series and the rate at which these decrease as the lag between pairs of values increases....

, which has been used in other fields, such as finance and cardiology, was named after him. His biography is found in the Hydrological Sciences Bulletin of December 1979.